package 数的三次方根;

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        double x = in.nextDouble();
        double l = -10000, r = 10000;
        while (r - l > 1e-8) {
            double mid = (l + r) / 2;
            if (mid * mid * mid >= x) {
                r = mid;
            } else {
                l = mid;
            }
        }
        System.out.printf("%.6f",l);
    }
}
